The gore level isn't higher it's really the emotional impact that's different. Frankly, things get pretty grim: Key characters die, and the villains are much scarier than most comic book baddies. The core plot element is mass murder on a universal scale, which might be a little much for younger viewers. Thanos ( Josh Brolin) is by far the most powerful nemesis the Avengers have faced, which the filmmakers establish right away with his brutal beatdown of one of the mightiest Avengers. Violence is the biggest issue it's stepped up even by MCU standards, with some torture and several impalings and crushings in addition to the usual smashed buildings, giant fights, and blasted spaceships. Also, it requires more knowledge of things that have happened in previous Marvel movies than other Avengers films have it's the meeting point of several franchises and storylines.
It has plenty of humor and lighter moments, but it ultimately goes to places darker than in any previous Marvel Cinematic Universe entry. Parents need to know that Avengers: Infinity War is the most intense of the Marvel Cinematic Universe films so far, due to the villain's genocidal quest and the grave consequences for some well-known characters.
